Condenser



Oct. 2, 1951 CAGE 2,569,655

CONDENSER Filed Dec. 1, 1948 2 Sheets-Sheet l mm 9 a INVENTOR. 7 M Cage J. M. CAGE CONDENSER Oct. 2, 1.951

2 Sheets-Sheet 2 Filed Dec. 1, 1948 Ill/1% INVENTOR.

Patented Oct. 2 1951 CONDENSER John M. Cage, Montclalr, N. J assignor to Cage Projects, Inc., Union City, N. J.,

of New Jersey a corporation Application December 1, 1948, Serial No. 62,843

4 Claims. 1 I

This invention relates to capacitors for use in electric circuits, as, for instance, high voltage power circuits for television and other similar high voltage applications.

One object of this invention is a, new and improved capacitor for high voltage circuits, that is characterized by its small size and its ability to withstand extremely high potentials.

Another object of this invention is a high voltage capacitor wherein extremely long leakage paths are maintained between the terminals thereof, and substantially uniform dielectric fields are maintained over the surface of the dielectric material.

Still another object of this invention is a new and improved capacitor of the character set forth that is economical to manufacture and is ad- Justable to'provide a wide range of capacities.

Another object of this invention is a new and improved condenser, particularly useful in high voltage power supplies for television equipment.

Another'object of this invention is a condenser bank for high voltage power supplies that will materially simplify the structure of these supplies, and at the 'same time materially reduce the formation of corona and breakdown of the condensers due to moisture and dirt settling on the surfaces thereof.

Still another object is a new and improved condenser.

' *These and otherobjects of this-invention will become more apparent from the following description taken in connection with the accompanying drawings forming a part of this application.

In the drawings, Figure 1 is'a cross-sectional view of one embodiment of this invention.

' Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1.

Fig. 3 is a perspective view of a part of one of the elements of the embodiment in Fig. 1 to illustrate certain details of the structure.

Fig. 4 is across-sectional view of another embodiment of this invention.

"Fig. 5 is a cross-section of the embodiment shown in Fig. 4 taken along the line 5-5 thereof.

Fig. 6 is still another modification of this invention.

Fig. 7 is a cross-sectlonal view of Fig. 6 taken along the line 5-6 thereof.

Fig. 8 illustrates still another embodiment.

Fig. 9 is an end view of the embodiment shown in Fig. 8.

Fig. 10 illustrates still another embodiment of this invention.

' greatly increased.

My new and improved capacitor overcomes many of the present diificulties encountered with present capacitors, and at the same time I am able to materially reduce manufacturing costs and produce a condenser somewhat smaller than conventional condensers of equivalent capacities and voltage ratings.

In Figs. 1, 2 and 3, I have illustrated one embodiment of my new and improved capacitor that can be adjusted over a relatively wide range of capacities during the manufacture thereof.

This form of the invention embodies dielectric material between the pole pieces which is formed in two parts, adapted to be abutted one against the other, and spacers, also of dielectric material, may be interposed between these parts to alter the capacity of the finished unit.

More particularly, the condensers consist of a pair of cup-like dielectric elements l0. These elements are preferably circular in shape and provided with plane end walls i0, adapted to be abutted one against the other.

In the present embodiment, I have illustrated a pair of spacers l2 interposed between the surface IU of the dielectric elements Hi to decrease the capacity of the condensers, and of course at the same time to increase the voltage rating thereof.

The inner surface I of the cups I0 is generally spherical in shape, and is preferably coated with a, thin layer of silver IE or other suitable conductin material. I prefer silver because of its non-corrosive characteristics, although under certain circumstances, as will appear hereafter. other materials, such as copper and lead, can also be used. The wall it of the cup I0 is preferably extended somewhat beyond the termination of the coating IS on the spherical part of the dielectric element, to increase the leakage path between the terminals of the condenser, and thereby effect a further increase in operating potential of the condenser. Each element III in its finished form resembles generally a pianoconcave lens, and when the elements are placed together in the manner previously described, they in effect form a bi-concave structure.

' and be soldered to the silver coating 16 on the element HI, and a rod-like or terminal part 20, formed integrally therewith and extending outwardly for the attachment of wires, or for making suitable connections to the condensers.

The elements ll, together with a part of the terminals 20 are then inserted in a cylindrical housing 26, which extends somewhat beyond the wall 18. The housing is then preferably closed at its ends by the end walls 28, having openings 30 to receive and lend added support to the outwardly extending terminal parts 24.

A particularly good dielectric material for the fabrication of the elements III, as well as the spacers i2, is titanium oxide, which has a dielectric constant of about 5000-K. The housin 26 and the end walls 28 may also be formed of titanium oxide, although some other dielectric material may also be used.

The dielectric elements I and ID are held in the housing 26 by means of the end walls 28 cemented to the housing 26 and bearing against collars 24 and the terminal parts 24. I prefer to fill the entire unit with a suitable insulating paste such as silicone orthe like. The elements I0 and I! are also preferably held in position by a suitable high dielectric cement.

From the foregoing description of one embodiment of this invention, it is apparent that I have been able to materially increase the leakage path from one terminal to the other because the shortest distance between two terminals 20 is over the external surface of the condenser, and voltage cannot leak from one silver coating ii to the other over the outer surface of the elements l0.

Furthermore, an electrostatic field produced in a condenser, when a potential is applied thereto, is usually very much greater at the edges of the poles, which in this instance are the silver coatings l6, than at the center. By fabricating the condensers in the manner described, I have provided the thickest part of the dielectric at the edges thereof, so that I am able to obtain a. substantiallyuniform electrostatic field throughout the entire dielectric.

Another advantage of this structure resides in the employment of two individual elements l0 between which can be placed one or more spacers i2 to produce condensers of different values and without involving any material changes in the manufacturing process, and without altering the size or shape of any of the component parts thereof.

Figs. 4 and 5 illustrate another embodiment of this invention to further increase the leakage path over the surface of the condenser.

In this embodiment I have illustrated the elements Hi of Fi 1 as being formed of one piece and have denoted it in the figure by the numeral 40. I have also illustrated in this figure the outer housing as being formed integrally with the dielectric element 40, and have denoted this housing by the numeral 42. The other elements of the condenser illustrated in this figure are similar to those shown in Fig. 1, and have been indicated by like numerals.

The outer housing 42 is provided with a series of grooves or serrations 44 on the outer surface thereof, with each groove or serration completely encircling the housing. In this way the length of the leakage path over the surface of the condenser is increased to approximately twice the distance of a straight line path, and will therefore withstand voltages materially higher than those shown in Fig. 1. This is particularly important in damp and humid climates wherein the component parts of a television set, for example, are in a protected position and are usually at a lower temperature than the surrounding atmosphere. Under these conditions, of course, moisture will readily condense on the parts, and, in the Presence of dirt and other foreign matter which settles on the surfaces of these parts, forms a conducting path. By maintaining the conducting path extremely long, as in the present embodiment, the presence of breakdown can be materially reduced, even under adverse conditions. It is, of course, possible to serrate or ridge the outer surface of the housing 25 in Fig. 1 in substantially the same manner as illustrated in 44 in Fig. 4, with the same and desirable and beneficial results.

In Figs. 6 and '7, I have shown another modiflcation of my new and improved condenser, which embodies certain of the advantages shown in Figs. 1 and 4. In this figure the dielectric elements are denoted by the numeral 50 and are cemented in abutting relationship in the outer housing 52 in substantially the same manner as heretobefore described in connection with the element III in Fig. 1. I have also illustrated in this figure the employment of two spacers 54 interposed between the elements 80. The elements in this form of the invention are provided with end walls 56, having substantially flat inner surfaces 58, on which is deposited a suitable silver or other metallic coating I. The condenser terminals il are each provided with heads 62 having an outer contour resembling that of a toroid, and having a flat surface thereon to abut and be secured to the silver layers ll. This outer housing 52 may, of course, be ridged in the manner shown in Fig. 4, and the ends of this housing are of course preferably closed by end walls 64, cemented to the housing 52. Because of the particular structure of the elements 50, the manufacturing problem may be somewhat simplified and therefore under certain conditions, this structure would be preferred.

In each of the embodiments heretofore described, the layer II has been indicated as being a layer of silver. I prefer to apply the silver in the form of a paint consisting of powdered silver suspended in a suitable organic binder solution that can be readily applied in any suitable manner to the desired surfaces.

The painted parts are then preferably baked at a temperature of approximately 800 C. to harden the silver and cause it to adhere to the walls of the element. The terminals of the condenser can then be readily soldered or sweated in place at the center of the silver layer. This method of forming the silver coating and adhering the silver to that coating provides a secure connection, and with the added support provided by the end walls of the housing, a rigid structure is obtained.

To further improve the condenser and reduce corona losses, I prefer to fill the cavities between the end walls of the housings and the inner surface of the elements with a suitable insulating material, such as silicone insulating paste. A silicone is a substance wherein each molecule includes an atom of silicon bonded directly to an atom of carbon.

In each of the previous embodiments of the invention separate and walls are provided for the cylindrical housing to enclose the dielectric elements. In the alternative, the housing and the end walls can be fabricated in one piece, with the housing split circumferentially so that the individual parts or halves can be slipped over the ends of the pole pieces to enclose the condenser and then suitably'cemented together to form a unitary structure.

I have illustrated such a structure in Figs. 8 and 9, and have illustrated in these figures cylindrically shaped elements I0, having a pair of somewhat thinner elements or spacers I2 interposed therebetween. The outer surfaces of the elements I are again provided with a suitable coating I0, having pole pieces I4 fastened thereto in the manner described in connection with the previous figures.

The outer housing 10, in this modification, consists of two cylindrically shaped cup-like parts I8 and 00. The end walls of these housing parts are relatively thick and are provided with center openings I0 and 00 terminating in inner recesses I! and II, respectively, to receive the terminals I4 of the condenser. These housing parts I0 and 00 completely enclose the condenser elements and part of the terminals and may be coated with silicone paste or cemented to the condenser elements by a suitable high dielectric cement. The edges of the housing halves are also cemented together along the line 02 to form a rigid unitary structure. It may also be desirable to cement the terminals I4 in the openings I0 and 00, and to fill the openings between the silver layers 10 and the adjoining face of the housing parts with silicone or other suitable insulating material, which may be in the form of a paste.

This condenser structure is particularly useful in certain types of high voltage power supply circuits wherein two or more of the condensers are connected in series as well as with other components of the power supply. An outstanding example resides in the voltage multiplier type power supply wherein three or more rectifier tubes are connected to a radio frequency power source to both multiply and rectify the voltage. In an application employing say five rectifier tubes, a bank of three series connected condensers, and a bank of two series connected condensers, are employed. In the use of individual condensers in an application of this character, where voltages of as high as 100 kv. are developed, large corona losses are experienced at the terminals of the condensers as well as each condenser must be very well insulated from associated components to prevent any breakdown between the components.

My new and improved condenser lends itself readily to power supplies of this character in that I can arrange two or more of the condensers, connected in series, within a single housing of the insulated material to prevent the collection of moisture and dust about the condenser parts, and in addition I can provide direct connections between the condensers that are free from sharp corners and uneven surfaces, primarily responsible for the generation of corona in high voltage circuits.

Such a structure is illustrated in Fig. 10, which shows three individual condensers, mounted within a single housing, and which may either be evacuated or filled with a suitable insulating material, such as the silicone paste previously referred to.

The three dielectric elements are indicated in this figure by the numeral 00 and are in the form of Iii-concave elements, with the concavity being spherical in shape. Each of the elements 00 is provided with three or more projections 02 extending from the edge thereof to slidably contact the inner surface of the cylindrical housing 04. The elements 00 are each provided with suitable silver coating II, as previously described in connection with other figures, and are held in spaced relationship within the housing 04 by terminals or conductors 00 interposed between the elements 00. Conductors 00 are each provided with end portions 00 adapted to be soldered or otherwise suitably fastened to the silver layers l0.

At the righthand end of the housing 04 is a short tubular insulating member 00 secured to the end of the housing and having a small projection I00 on its inner end to receive and hold one end of a small spring I02. Between this spring I02 and the adjoining silvered surface of the element 00 is a condenser terminal I04 fastened at one end I00 to the silvered surface I0 and having at its other end the small projection I08 for engagement with the other end of the spring I02. The element farthest to the left is providedwith terminal I00 which is suitably fastened to the adjoining silvered layer I0 on the element and has on its outer end a projection H0 of reduced section for engagement with an opening I I2 in the end wall I I4 on tube 84.

In the assembly of these condensers within the tube the condenser terminals 96, I04 and I00 are first fastened to their respective silver layers with the elements 90 in proper alinement. The structure is then slid into the tube so that the projection I08 of the terminal I04 will engage the spring I02. The end wall I I4 of the tube 94 is then fitted over the projection I I0 of the terminal I00 and the entire assembly moved inwardly of the tube to compress the spring I02. The end wall II4 may then be suitably fastened to the tube 94 by glass welding or by applying a suitable cement to the edge thereof.

Connections for the several condensers are made through the wires H6 fastened to the con denser terminals 96, I04 and I00. These connections are brought through openings H0 in the wall of the tube 94. As the condensers are assembled within the tube and the leads Iii are brought out through the openings IIO, the openings are then closed by applying a cementing compound, or by melting glass about the wires II at the points where they emerge from the tube 94. In this way a completely sealed unit is obtained that will be relatively unaffected by moisture and foreign matter on the outer surfaces thereof.

If desired, the openings H8 in the tube 94 can be staggered about the circumference thereof in order to increase the leakage path between the terminals and also to provide shorter leads between the components of the power supply.

From the foregoing description it is apparent that the condenser structure can be evacuated by any conventional process, or, in the alternative, it may be completely filled with a silicone insulating paste or other similar insulating material and then sealed against the admission of moisture or other foreign matter.

In each of the embodiments of this invention I tain other modifications and changes canbe made in the embodiment herein illustrated without departing from the true scope of this invention. Furthermore, the concavities of the elements may be parabolic or have other contours and the outer surface of the tube 84 in Fig. 10 may be ridged similar to the outer housing of the embodiment shownin Fig. 4.

Certain of the matter disclosed herein is disclosed and claimed in an application filed by applicant on February 6, 1951, Serial No. 209,563.

I claim:

1. A condenser comprising a housing of dielectric material, a pair of terminals each having one end thereof extending from the housing, the inner ends of said terminals being separated by a pair of dielectric elements adapted to' be placed in overlying relationship one with-the other, conductive surfaces on the outer side of each element forthe attachment of its respective terminal and spacer ing of dielectric material, a pair of piano-concave dielectric elements in said housing with the plane surfaces in overlying relationship, a conductive coating on the concave surface of each element, dielectric spacers between said overlying surfaces of said elements to separate said elements, and metallic terminals secured to said conductive coatings.

4. A condenser comprising a cylindrical housing of dielectric material, a pair of'plano-concave dielectric elements in said housing with the plane surfaces thereof in overlying relationship, and conductive terminal means placed against and conforming with the concave surface of each element,"saidelements being adapted to receive dielectric means interposed between the overlying surfaces to hold them in spaced relationship.

JOHN M. CAGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,797,878 Palm Mar; 24L'1931 2,303,391 Rosenthal Dec. 1, 1942 FOREIGN PATENTS Number Country Date 601,961 Germany Aug. 28, 1934 562,100 Great Britain June 19, 1944 

